playground: tiproxy needs to override usercfg

[xhebox]

What problem does this PR solve?

Close #2339

previously, it doesnt override user config correctly leading to port conflicts when using custom configs for multiple tiproxy instances. TiDB pass ports by cli flags so then are fine.

Also, log-file is not passed

What is changed and how it works?

1. use different logic than TiDB to generate configs.
2. pass log-file

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No code

Code changes

• Has exported function/method change
• Has exported variable/fields change
• Has interface methods change
• Has persistent data change

Side effects

• Possible performance regression
• Increased code complexity
• Breaking backward compatibility

Related changes

• Need to cherry-pick to the release branch
• Need to update the documentation

Release notes:

NONE

[codecov-commenter]

Codecov Report

Attention: 16 lines in your changes are missing coverage. Please review.

Comparison is base (48b5119) 55.42% compared to head (4145baf) 55.05%.
Report is 1 commits behind head on master.

❗ Current head 4145baf differs from pull request most recent head 4df235a. Consider uploading reports for the commit 4df235a to get more accurate results

Files	Patch %	Lines
components/playground/instance/tiproxy.go	0.00%	16 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2342      +/-   ##
==========================================
- Coverage   55.42%   55.05%   -0.37%     
==========================================
  Files         328      328              
  Lines       34828    34827       -1     
==========================================
- Hits        19300    19172     -128     
- Misses      13218    13356     +138     
+ Partials     2310     2299      -11     

Flag	Coverage Δ
cluster	44.30% <ø> (-0.44%)	⬇️
dm	25.45% <ø> (-0.02%)	⬇️
playground	15.32% <0.00%> (+0.02%)	⬆️
tiup	33.56% <ø> (-0.05%)	⬇️
unittest	22.35% <ø> (ø)

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[kaaaaaaang]

/lgtm

[kaaaaaaang]

/approve

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: kaaaaaaang

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• OWNERS [kaaaaaaang]

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[kaaaaaaang]

/lgtm

[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2023-12-28 09:10:40.996061608 +0000 UTC m=+1729732.033288530: ☑️ agreed by kaaaaaaang.
• 2023-12-29 07:22:51.806774186 +0000 UTC m=+1809662.844001113: ✖️🔁 reset by ti-chi-bot[bot].
• 2023-12-29 07:23:57.731474982 +0000 UTC m=+1809728.768701913: ☑️ agreed by kaaaaaaang.